From f0e6b25ed2182f0075915a806c087da890de1ccf Mon Sep 17 00:00:00 2001
From: Anthony Fieroni <bvbfan@abv.bg>
Date: Wed, 24 Nov 2021 14:29:57 +0200
Subject: [PATCH] Simplify writers flush / discard

Signed-off-by: Anthony Fieroni <bvbfan@abv.bg>
---
 src/masternodes/accountshistory.h | 24 ++++++++++++++++++
 src/validation.cpp                | 42 ++++---------------------------
 2 files changed, 29 insertions(+), 37 deletions(-)

diff --git a/src/masternodes/accountshistory.h b/src/masternodes/accountshistory.h
index 20469cd8cbd..53cd278f2ff 100644
--- a/src/masternodes/accountshistory.h
+++ b/src/masternodes/accountshistory.h
@@ -126,6 +126,30 @@ class CAccountsHistoryWriter : public CCustomCSView
     bool Flush();
 };
 
+template<typename T, typename... Args>
+inline void FlushWriters(std::unique_ptr<T>& writer, Args&... args)
+{
+    static_assert(std::is_base_of<CStorageView, T>::value, "T should inherit CStorageView");
+    if (writer) {
+        writer->Flush();
+    }
+    if constexpr (sizeof...(Args) != 0) {
+        FlushWriters(args...);
+    }
+}
+
+template<typename T, typename... Args>
+inline void DiscardWriters(std::unique_ptr<T>& writer, Args&... args)
+{
+    static_assert(std::is_base_of<CStorageView, T>::value, "T should inherit CStorageView");
+    if (writer) {
+        writer->Discard();
+    }
+    if constexpr (sizeof...(Args) != 0) {
+        DiscardWriters(args...);
+    }
+}
+
 extern std::unique_ptr<CAccountHistoryStorage> paccountHistoryDB;
 extern std::unique_ptr<CBurnHistoryStorage> pburnHistoryDB;
 
diff --git a/src/validation.cpp b/src/validation.cpp
index 45d21252e8a..e150e89b6da 100644
--- a/src/validation.cpp
+++ b/src/validation.cpp
@@ -3538,32 +3538,16 @@ bool CChainState::DisconnectTip(CValidationState& state, const CChainParams& cha
         assert(view.GetBestBlock() == pindexDelete->GetBlockHash());
         std::vector<CAnchorConfirmMessage> disconnectedConfirms;
         if (DisconnectBlock(block, pindexDelete, view, mnview, disconnectedConfirms) != DISCONNECT_OK) {
-            // no usable history
-            if (paccountHistoryDB) {
-                paccountHistoryDB->Discard();
-            }
-            if (pburnHistoryDB) {
-                pburnHistoryDB->Discard();
-            }
-            if (pvaultHistoryDB) {
-                pvaultHistoryDB->Discard();
-            }
             m_disconnectTip = false;
+            // no usable history
+            DiscardWriters(paccountHistoryDB, pburnHistoryDB, pvaultHistoryDB);
             return error("DisconnectTip(): DisconnectBlock %s failed", pindexDelete->GetBlockHash().ToString());
         }
         bool flushed = view.Flush() && mnview.Flush();
         assert(flushed);
 
         // flush history
-        if (paccountHistoryDB) {
-            paccountHistoryDB->Flush();
-        }
-        if (pburnHistoryDB) {
-            pburnHistoryDB->Flush();
-        }
-        if (pvaultHistoryDB) {
-            pvaultHistoryDB->Flush();
-        }
+        FlushWriters(paccountHistoryDB, pburnHistoryDB, pvaultHistoryDB);
 
         if (!disconnectedConfirms.empty()) {
             for (auto const & confirm : disconnectedConfirms) {
@@ -3709,15 +3693,7 @@ bool CChainState::ConnectTip(CValidationState& state, const CChainParams& chainp
                 InvalidBlockFound(pindexNew, state);
             }
             // no usable history
-            if (paccountHistoryDB) {
-                paccountHistoryDB->Discard();
-            }
-            if (pburnHistoryDB) {
-                pburnHistoryDB->Discard();
-            }
-            if (pvaultHistoryDB) {
-                pvaultHistoryDB->Discard();
-            }
+            DiscardWriters(paccountHistoryDB, pburnHistoryDB, pvaultHistoryDB);
             return error("%s: ConnectBlock %s failed, %s", __func__, pindexNew->GetBlockHash().ToString(), FormatStateMessage(state));
         }
         nTime3 = GetTimeMicros(); nTimeConnectTotal += nTime3 - nTime2;
@@ -3726,15 +3702,7 @@ bool CChainState::ConnectTip(CValidationState& state, const CChainParams& chainp
         assert(flushed);
 
         // flush history
-        if (paccountHistoryDB) {
-            paccountHistoryDB->Flush();
-        }
-        if (pburnHistoryDB) {
-            pburnHistoryDB->Flush();
-        }
-        if (pvaultHistoryDB) {
-            pvaultHistoryDB->Flush();
-        }
+        FlushWriters(paccountHistoryDB, pburnHistoryDB, pvaultHistoryDB);
 
         // anchor rewards re-voting etc...
         if (!rewardedAnchors.empty()) {